The X-Phase-2 QRM-killer Picture: Luit Popken PA0LPN Developed originally by G4WMX and GW3DIX, later improved by DK9NL. Latest improvements by DG0KW (version used by us)
A hobby project of the local VERON and VRZA departments Wageningen/Ede, Netherlands Professionally developed and produced PCB s Component kits for the PCB s made available
Problem to be solved. antenna exciting DX Nearby noise sources make DX unreadable HAM hears exciting DX QRM source
.. And the solution! antenna exciting DX QRM killer added between antenna and transceiver HAM hears exciting DX auxiliaryantenna Noise source Auxiliary antenna picks up noise from source Adjust QRM killer to eliminate noise
Principle of killing the local QRM Picked up QRM via main antenna (desired DX- signal not shown) Picked up QRM via auxiliary antenna (amplitude and phase differs from QRM added on main signal) Use middle and right potmeter (Phase 1 en Phase 2) to shift the phase of the auxiliary QRM 180 degrees with respect to the QRM via the main antenna Use left potmeter potmeter to make the QRM on the main signal equal in amplitude of the auxiliary signal Result: QRM disappears almost entirely
Tips and tricks QRM must come from a local source (within a radius of 100m) Auxiliary antenna must not be too good. You need a strong QRM signal on it and the desired signal must be relatively weak Operating the QRM killer is easy. You will soon get used to the knob fiddling to eliminate the QRM Centre and right potmeter are for phase shifting the auxiliary signal. Left potmeter is for adjusting the amplitude of the main signal Reduction of the QRM is quite good in most cases.
X-Phase block diagram XMIT command from transceiver TRX Main antenna VOX circuit Relaycontrol gain Phase 2 Phase 1 RX/TX relay Summing amplifier and gain control Phase shifter Aux antenna
Schematic diagram
The assembled printed circuit board Nominated for Miss PCB beauty contest
Design aspects - Professionally designed and fabricated PCB, double sided, through hole metallized and silk screen - RF connections on board are as short as possible - PCB top layer is used as ground plane
Signal path during transmission n/c contacts of RY1 are wired in parallel to keep the signal path at a low impedance (the 100W Xmitter output will flow through it!)
Signal path during receiving D1 to D8 are protection diodes
Phase shifting circuit details The phase of the auxiliary signal can be shifted over a wide rang by adjusting potmeters R6 and R8. Note that both potmeters also have an influence on the amplitude of the AUX-QRM signal.
Summing amplifier Signals from the main antenna enter the amplifier via the gate of T1. The auxiliary signal enters the summing amplifier via the gate of T2. Both signals are added at the coupled drains of T1 and T2. If the QRM component on both signals are equal in amplitude and differ 180 degrees in phase, both QRM signals cancel each other. The cleaned up signal from the main antenna is fed to the transceiver via C4.
VOX and TX/RX switching Note that the relays are NOT activated during transmission. They will be activated during reception. This is a safety precaution. If you forget to switch on the power of the X-Phase, the transmitter power cannot destroy the circuitry but flows directly to the antenna. VOX: the transmitter is rectified by D10 and D11. The generated negative voltage shuts down T3 which in turn switches off the relays. De VOX is only meant as a safety precaution in case the TX/RX control signal coming from the transceiver fails. This control signal enters the circuit via J5 and pulls J5 to ground during transmission.
Assembly of the PCB is easy Please watch carefully the polarity of diodes and electrolytic capacitors
Component placement
Step 1: resistor placement
Step 2: diode placement DO mind the diode polarity! DO mind D15! This is a Schottky diode (BAT85) and looks deceptively the same as the 1N4148!
Step 3: capacitor placement Mind the polarity of (C12 and C15).
Coil winding Start with the secondary winding (33 wdg, 0.3 mm dia) On top of that the 7 windings of 0.4 mm dia wire Make sure that you connect the transformer in the proper way (see next slide)
Placement of the transformer Primary winding (7 wdg 0.4mm) Secondary winding (33 wdg 0.3mm)
Stap 4: assembly of all other components First, solder the two SMD FET s before placing the taller components.
The final result, a real beauty!
External connections (on front panel) ON/OFF switch (on back panel) Back-panel TX/RX cntrl PTT TRX-Gnd +12V 0 V AUX. antenna Main antenna Backpanel Pwr ON TX-ON (on front panel)
Co-axial antenna connections Keep connections as short as possible. Use 2 or more ape tails for Ground connections Plastic shield coax cable Outer metal shield Solder tag Twisted part of outer metal shield ape tail ) core Coax connector
Connecting the coax cable to the PCB U-bend short lengths of thin wire and solder them in the Ground pads.now it is easy to solder the ape tails to the PCB. You can use thin RG174/U cable. It can handle over 400W of RF power!
DON T do it this way!!! This way of connecting the main antenna and transceiver are BREATH TAKING! The single wires form a large self-inductance because the return signal must find it s way through the cabinet wall. ALWAYS use coaxial cable with GROUND connections at both ends!
Tips: Soldering a plated through hole PCB: put your soldering iron on the pad and component wire for 3 seconds, apply enough solder and wait another 3 seconds. In this way the heat gets through the hole and wire and the and allow the solder to flow through the hole. Removing a component: DON t be rough by putting a screwdriver under the component and forcing the component out while heating the solder. Instead: cut the component wires on both sides, heat up the solder of each pad and remove the end of each wire carefully with a tweezer. Use solder sucking wick to clean up the hole.
More tips: Maximum allowable transmitter power: the X-Phase can be used with output powers up to 200 W. But if you use a linear amplifier, connect the X-Phase between the transceiver and the INPUT of the linear. VOX circuit: resistor R9 is chosen to let de VOX circuit work from 40 Watt transmitter power or more. If you want to let the VOX operate at lower power levels, just lower the value of R9. But ONLY if you don t use higher power levels Interchanging the + and - 12V connections is not harmful. A series diode protects the circuit against reverse polarisation
Boxing the PCB picture: Luit Popken PA0LPN Two bolts and spacers support the PCB at the back side
The finished X-Phase picture: Luit Popken PA0LPN
And the good looking backside picture: Luit Popken PA0LPN
Drilling diagram of the front side drilling plan: Luit Popken, PA0LPN
Backside drilling plan Drilling plan: Luit Popken, PA0LPN
Test 1: (is there a connection between antenna and transceiver via the X-Phase?) antenna Connect the transceiver on the X-Phase Adjust the transceiver output power to LOW (as a precaution) Connect the antenna to the X-Phase Connect a 12V power supply to the X- Phase TRX ant AUX-ant X-Phase Turn the GAIN potmeter fully clockwise Check if you hear the normal radio traffic. You can attenuate the reception by the left potmeter If this all is OK, the summing amplifier is working correctly
Test 2: is the X-Phase working correctly? antenna Coax T-adaptor TRX ant AUX-ant X-Phase Connect the main antenna to BOTH the main antenna input and the Auxiliary antenna input via a coaxial T-adaptor. Switch on the power supply Try to minimize the incoming signals by adjusting the three potmeters If everything is OK, all signals will almost disappear
Setting up a station with the X-Phase Most transceivers have an accessory socket on the backside of the set. One of the pins carry the TX-on command signal. Mostly, this pin is connected to ground by the transceiver during transmission. Prepare a connection cable between transceiver and X-Phase to bring the TX-on command to the X-Phase (connect TRX-ground to X-Phase ground and the TX-on pin of the transceiver to J5 of the X-Phase) TIP: when this cable is ready, connect the X-Phase to the transceiver but DO NOT connect the antenna to the transceiver via the X-Phase. Use a dummy load or connect the antenna directly to the transceiver. Press the transmit key and look if the red LED on the X-Phase illuminates. If this is OK, the moment has come to connect the X-phase between the antenna and the transceiver (see next slide) and start working with it.
Definitive connections antenna Complete hook-up of the X- Phase in the station TX-on Control cable auxiliary antenna Minimize the QRM with the three potmeters. Try to keep the GAIN potmeter as much as clockwise (first minimize the QRM with the two PHASE potmeters). TRX ant aux-ant X-Phase
How to connect the X-phase when using a linear amplifier NEVER put the X- Phase between the Linear output and the antenna!!! antenna Auxiliaryantenna
Kits can be made available PCB only: 9 Euro Complete kit with PCB and all components for assembling the PCB including the 3 potmeters: 30 Euro If SMD soldering of the two FET s is a problem: we can do this in advance for you without charge Detailed assembly and test instructions are available on our website: A43.VERON.NL
Bill of materials aantal waarde benaming steek aantal waarde benaming steek 2 22E WEERSTAND 10mm 1 1mH RF SMOORSPOEL 16 mm 1 56E WEERSTAND 10mm 1 FT50-43 ringkerntrafo 2 wdg 1 120E WEERSTAND 10mm 1 150E/0,5W WEERSTAND 10mm 12 1N4148 diode 7,5 mm 2 1k2 WEERSTAND 10mm 2 1N4001 power diode 10 mm 1 2k2/2W WEERSTAND 18 mm 1 BAT85 BAT85/Schottky DO-35 3 2k2 potmeter 2 x 5 mm 1 rood LED 3mm 2,5 mm 1 22k WEERSTAND 10mm 1 groen LED 3mm 2,5 mm 1 1M WEERSTAND 10mm 1 BC337 NPN transistor TO92 2 MMBFJ310 J-FET SOT23T 1 47pF/1000V CONDENSATOR 5 mm 2 DIP power relais 2 x om Farnell 1629053 2 68pF CONDENSATOR 2,5 mm 3 1nF CONDENSATOR 2,5 mm 7 10nF CONDENSATOR 2,5 mm 1 100nF CONDENSATOR 2,5 mm 1 100uF/25V ELCO-TM 2,5 mm 1 470uF/25V ELCO-TM 3,5 mm
Resistor colour codes (4 rings)
Resistor colour codes (5 rings)
Capacitor value coding
Inductance colour codes Value in micro-henry